Historic sedimentation and allostratigraphy of the South Fork Broad River, northeast Georgia
Lichtenstein, Karin Prest
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The arrival of Euro-American agricultural practices (circa A.D. 1820) to the southern Piedmont introduced landuse change that caused rapid floodplain sedimentation in the South Fork Broad River. Stratigraphic sampling of 34 sites indicates that the average thickness of historic sediment stored within the valley bottoms is 0.89 m. A volumetric analysis using GIS indicates that historic (A.D. 1820 - A.D. 2001) sediment yields were greater than 829 tonnes/km2/yr. An allostratigraphic framework is applied to the recent floodplain sediment and is based on lithology, unconformable boundaries, landscape morphology, and relative pedogenic development. Accompanying factors such as texture, color, stratigraphic position, radiocarbon dates and organic carbon content are also used for classification. The use of GIS applications and allostratigraphy provides information about past sediment yields in relation to present-day sediment yield estimates and offers important background data for assessments of the Total Maximum Daily Load of sediment.